We estimated mean volumes of 38 trillion cubic feet (TCF) of undiscovered natural gas, 159 million barrels of natural gas liquid (MMBNGL), and no oil in accumulations of 0.5 million barrels (MMBO) or larger in this area.

We estimated undiscovered, technically recoverable resources are 534 billion cubic feet of natural gas and 323 thousand barrels of natural gas liquids in this area using a geology-based assessment methodology.

We estimate mean volumes of 896 million barrels of oil and about 53 trillion cubic feet of nonassociated natural gas in conventional, undiscovered accumulations within this area, a reduction of our 2002 estimate due to new geologic information.

The Marcellus shale is a black shale unit in the eastern US. It has economic use as a source of natural gas. Environmental concerns arising from the process of exploiting this resource include water supply and wastewater disposal.

Brief descriptions, contacts, and links to other information and products for research programs of the USGS Central Energy Team on gas hydrates, petroleum expulsion, unconventional natural gas, petroleum systems, and reserve growth.

Using a geology-based assessment methodology, we estimated means of 565 billion barrels of conventional oil and 5,606 trillion cubic feet of undiscovered conventional natural gas in 171 priority geologic provinces of the world, exclusive of the U.S.